The immune system is a defense system for protecting a subject against potentially harmful substances such as microorganisms, toxins, cancer cells, blood or tissues of another subject. The immune system is composed of two major subdivisions, the innate immune system and the acquired immune system. The innate immunity system, also called the non-specific immune system, is the first line of defense, which provides immediate protection; its major components include natural killers, macrophages, neutrophils, eosinophils, etc. The acquired immunity system, also called the specific immune system, acts as the second line of defense, which requires some time to react to a specific antigen; its major components include T cells and B cells.
The acquired immune system comprises two types of immune responses, T-helper-1 (Th1)-type and T-helper-2 (Th2)-type. Th1-type responses provide cell-mediated immunity, involving secretion of interleukin-2 (IL-2) and interferon-r (IFN-r), and activation of cytotoxic lymphocytes (CTLs), which can provide protection against viral infection and cancer cells. Th2-type responses provide humoral immunity, involving secretion of interleukin-4 (IL-4) and interleukin-5 (IL-5) and activation of B cells, which can provide protection against free bacteria or parasites. However, over secretion of IL-4 and IL-5 is related to allergy and inflammation.
Immunity can result from either passive or active immunization. Active immunization produce immunity against a certain foreign substance (e.g. a pathogen) after the body is exposed to it and thus activated to produce such immunity. On the other hand, passive immunization involves transfer of immune components (typically antibodies) against a particular pathogen from one individual to another; the body per se however does not actively produce the immunity. In general, active immunization requires relatively longer time to produce the immunity which is lasting while passive immunity provides faster immunity which is not lasting.
U.S. Pat. No. 6,464,982 describes an immune system stimulator comprising a variety of herbals, which results in secretion of IL-1 without causing an increase in production of IL-4.
Pathogen specific antibodies can be isolated from egg-yolk of hens which have been immunized with the pathogen as an antigen for use in passive immunotherapy for treatment of certain diseases caused by the pathogen. This technique has been developed for many years and isolation of antibodies to common pathogens causing diarrhea, such as Salmonella Bacillus (American Journal of Veterinary Research 59:416-20) and the Annular virus (Journal of Infectious Diseases 142:439-41 and Archives of Virology 138:143-8), using this technique have been reported. The period of diarrhea can be reduced after administration of such antibodies to patients in need. Shin et al. reported that antibodies specific to Helicobacter pylori can be isolated from egg yolk of hens immunized with H. pylori and described that such isolated antibodies can be used for treatment of infectious diseases caused by H. pylori (Clinical and Diagnostic Laboratory Immunology, 9(5): 1061-1066). Marquardt et al. (U.S. Pat. No. 7,355,092) disclosed genetic vaccines against E. coli fimbrial antigens and a method for isolating antibodies from chicken egg yolk for passive immunization of animals to control diarrhoeal diseases using the genetic vaccines.